Tag Archives: Article

Whilst we know a lot about the foraging preferences of honey bees, little is known about the foraging preferences of bumblebees. In this new study, we show that whilst the majority of foraging bumblebees are generalists (feeding on both pollen and nectar), some bumblebees do specialise on only foraging for pollen, and some specialise on nectar. Believing this may be linked to the different sizes of bumblebee foragers that a colony produces, we set about looking for relationships between this foraging preference and the body size, fat content, sucrose sensitivity and ovary size of the workers.

To learn more about this work, which was led by Dr Adam Smith (now at George Washington University), please click here

The bumblebee industry relies heavily on pollen to feed the bees. This pollen is harvested from the legs of honeybees then fed to bumblebees. The problem with this is that it may contain parasites that are infective to bumblebees!

By working in collaboration with one of the largest global suppliers of bumblebees (Biobest), the English regulating body (Natural England), the Bumblebee Conservation Trust, and funded by NERC, we move a step closer to reducing parasite spread in bees! This new article details exactly how much of the different, know parasites, are found in pollen intended for bumblebee feed. Then, we test how abundant these parasites are when the pollen is treated with sterilisation processes including Gamma irradiation and a new ‘O-zone sterilisation’ technique. Finally, we feed bumblebees the different pollens and monitor their survival and physiology.

The results of this directly inform Biobest and other bumblebee breeders on what methods better maintain parasite free bumblebees, thus reducing the potential for global parasite spread.

The deformed wing virus (DWV), known to be ubiquitous in honey bees, has now been detected in bumblebees. In addition, the neogregarine Apicystis bombi has been discovered to be more prevalent than previously thought. Here, we assess for the first time the lethal and sublethal effects of these parasites during single and mixed infections of worker bumblebees (Bombus terrestris). Overall, we find that A. bombi exhibits both lethal and sublethal effects. DWV causes lethal effect and may reduce the sub lethal effects imposed by A. bombi. The results show that both parasites have significant, negative effects on bumblebee health, making them potentially of conservation concern

I have recently completed a review of research looking at disease in wild bees that are near managed honey bees and managed bumblebees.

In this work, I list the problems managed bees cause with specific examples from America, Asia and Europe and based on the evidence, suggest what practices could reduce the harm managed bees do to wild bees. We recommend first that the safety of bee transport be improved by employing rigorous disease screening of bees and creating unified international regulations to prevent the movement of diseased bees. Second, we advise that the mixing of managed bumblebees with wild bees should be prevented by using nets over glasshouses containing managed bumblebees. Finally, we recommend an increased conservation effort to limit the effects of managed bee use in areas suffering wild bee declines.

In this review I also give an overview of the history of the commercialisation of bumblebees – a relatively new industry.

Today some more of my research was published. In it I show that diseased bees deposit parasites on to the flowers they visit. These parasites can then infect healthy bees visiting the same flowers, or be transported by an unsusceptible bee species to other flowers to reach their host species.

I allowed bumblebees from hives infected with three different bumblebee diseases to forage on a patch of flowers in a flight cage for a period of 3 hours before removing them from the cage. Then I released disease-free honey bees into the cage and allowed them to forage for a further 3 hours on the same flowers, as well as a patch of uncontaminated flowers which were brought in at the same time. Immediately afterwards, the shared flower patch, the honeybee only flower patch and the honey bees were all screened for the bumblebee parasites with alarming results. All three of the parasites were detected on the shared flowers, while two out of three were detected on the flowers which only the honeybees had access to, as well as inside the honeybee colonies.

The experiment was repeated using honeybees from hives infected with two honeybee diseases and disease-free bumblebees and yielded similarly worrying results. Both parasites were found on the shared flowers, as well as on the flowers which only bumblebees had access to, and one of the two parasites was detected inside the bumblebee colony.

The study also compared how two different flower types aid the dispersal of bee parasites, and found that bell shaped Fairy’ thimble flowers contained higher parasite loads than more open Pansy flowers. This is likely because the bees spend more time in contact with bell-shaped flowers than they do with more easily accessible open flowers.

These results suggest that flowers play an important role in the transmission of diseases between bees.

“The upshot of this is that a range of parasites in diseased bee populations, such as infectious imported bees, may spread to wild bee populations that forage on the same flowers. On a wider level, flowers as parasite hotspots suggests that areas where there is a lot of pollinator traffic per flower, for example areas with low flower density, may have high parasite dispersal between pollinators compared to areas with low pollinator traffic per flower, such as flower rich areas.”

Mixing with managed bees may be to blame for increased diseases in wild bumblebees, prompting concern for their conservation, scientists have warned. It has been discovered that bumblebees suffer from more parasites when they are collected from around sites using managed bees.

Managed honey bees and bumblebees are frequently used by apiarists and farmers for their honey production or pollination services. The introduction of managed bees can increase the number of pollinators competing for resources in a given area and this can have ramifications to native pollinators.

To celebrate a joint meeting on the subject of bee health hosted by the Biochemical Society, the British Ecological Society and the Society for Experimental Biology in January 2014, the BES has compiled this virtual issue on Pollinator Ecology. The included papers are drawn from all five journals and provide examples of the latest research in pollinator ecology from flower visitation and ecosystem services, to the effects of invasive pollinators, agriculture, pesticides and bee pathogens. We hope that this selection of papers will be of interest to researchers and stakeholders in this highly topical field.

The brood in an ant colony are most vulnerable to parasites because their individual defenses are limited, and the nest material in which ants live is also likely to be prone to colonization by potential parasites. Here, we investigate in two ant species whether adult workers use their antimicrobial secretions not only to protect each other but also to sanitize the vulnerable brood and nest material. We find that, in both leaf-cutting ants and weaver ants, the survival of the brood was reduced and the sporulation of parasitic fungi from them increased, when the workers nursing them lacked functional antimicrobial-producing glands. This was the case for both larvae that were experimentally treated with a fungal parasite (Metarhizium) and control larvae which developed infections of an opportunistic fungal parasite (Aspergillus). Similarly, fungi were more likely to grow on the nest material of both ant species if the glands of attending workers were blocked. The results show that the defense of brood and sanitization of nest material are important functions of the antimicrobial secretions of adult ants and that ubiquitous, opportunistic fungi may be a more important driver of the evolution of these defenses than rarer, specialist parasites.

A. bombi from Argentina and Europe share a common, relatively recent origin. The absence of genetic structure across space and host species suggests that A. bombi may be acting as an emergent infectious disease across bee taxa and continents.

Nosema ceranae, a known Asian parasite of honey bees, implicated in colony losses, is now infecting bumblebees! Following the parasites spread from Asian to European honey bees, Nosema ceranae is now found in most temperate countries.

After using sensitive molecular screening methods on almost 800 wild-caught bumblebees from the UK, I detect the honey bee parasite Nosema ceranae in several bumblebee species.

We find that following infection by this parasite, bumblebees show increased mortality and reduced sensitivity to sucrose (a measure of learning/foraging ability).

Discovering a high prevalence of Nosema ceranae in a range of bumblebees species is alarming and demonstrates the cosmopolitan adaptability of this parasite, spilling over from Asian honey bees to European honeybees and now becoming an emerging danger to bumblebees. Sadly, this also highlights yet another harmful threat faced by declining bumblebee populations.

Results from my newly published work, The Trojan hives highlights imported dangers to native pollinators. Over a million commercially produced bumblebee colonies are imported annually on a
global scale for the pollination of greenhouse crops. After importation, they interact with
other pollinators, with an associated risk of any parasites they carry infecting and harming
native bees.

Following 2 years of monitoring, my research has shown how the majority of commercial bumblebee hives we purchased in 2011 & 2012 contained harmful parasites.

We found microbial parasites in 77% of the commercially produced bumblebee colonies we purchased from three producers, which were imported on the basis of being free of parasites. Following this, we found that a number of these parasites were infective and detrimental to both bumblebees and honey bees.

The results demonstrate that commercially produced bumblebee colonies carry multiple, infectious parasites that pose a significant risk to other native and managed pollinators. More effective disease detection and management strategies are urgently needed to reduce the pathogen spillover threat from commercially produced bumblebees.

Here we used the generalist entomopathogenic fungus Metarhizium to compare the disease resistance of a species of a weaver ant, Polyrhachis dives, which has lost the metapleural gland, with that of the well-studied leaf-cutting ant Acromyrmex echinatior and two other ant species, Myrmica ruginodis and Formica fusca, all of which have metapleural glands.

It appears that the evolutionary loss of the metapleural gland does not result in reduced disease resistance in P. dives weaver ants, and that this at least in part may be due to the ants having antimicrobial venom and high self-grooming rates. The results therefore emphasise the importance of multiple, complementary mechanisms in the disease resistance of ant societies.